<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .blur:before,body{
        background: url(http://d.ifengimg.com/mw978_mh598/p1.ifengimg.com/a/2017_32/8c486ccfeb65851_size180_w950_h631.jpg) no-repeat;/****/
        -webkit-background-size:;
        background-size:cover;
        background-attachment:fixed;/****/
        height: 100%;
    }
    .blur{
        text-align: center;
        width: 80%;
        height: 200px;
        padding-top: 250px;
        margin: 0 auto;
        margin-top: 50px;
        position: relative;
        background: hsla(0,0%,100%,.3);/****/

    }
    .blur:before{

        position: absolute;
        content:"";
        right: 0;
        left: 0;
        top: 0;
        bottom: 0;
        z-index: -1;
        filter:blur(20px);/*****/
        margin: -20px;

    }
</style>
<body>
<div class="blur">
    这个是文字
</div>
</body>
</html>